1. Field of the Invention
The invention relates to premixing burners on the double-cone principle with, essentially, two hollow conical partial bodies which are interleaved in the flow direction and whose respective center lines are offset relative to one another, the adjacent walls of the two partial bodies forming tangential gaps in their longitudinal extent for the combustion air and gas inlet openings distributed in the longitudinal direction being provided in the region of the tangential gaps in the walls of the two partial bodies.
2. Discussion of Background
Such double-cone burners are known, for example, from EP-B1-0 321 809 and are described later with respect to FIG. 1 and 2. The fuel, natural gas in that case, is injected in the inlet gaps into the combustion air flowing from the compressor. This is done by means of a row of injection nozzles which are usually evenly distributed over the complete gap.
Thorough mixing of the fuel with the air is necessary in order to achieve reliable ignition of the mixture in the downstream combustion chamber and to achieve sufficient burn-out. Good mixing also contributes to avoiding so-called "hot spots" in the combustion chamber which, inter alia, lead to the formation of the undesirable NO.sub.x.
The abovementioned injection of the fuel by using classical means such as cross-jet mixers is difficult because the fuel itself has insufficient momentum to achieve the necessary large-scale distribution and fine-scale mixing.